rename ptr::from_exposed_addr -> ptr::with_exposed_provenance
As discussed on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/136281-t-opsem/topic/To.20expose.20or.20not.20to.20expose/near/427757066).
The old name, `from_exposed_addr`, makes little sense as it's not the address that is exposed, it's the provenance. (`ptr.expose_addr()` stays unchanged as we haven't found a better option yet. The intended interpretation is "expose the provenance and return the address".)
The new name nicely matches `ptr::without_provenance`.
Add `Ord::cmp` for primitives as a `BinOp` in MIR
Update: most of this OP was written months ago. See https://github.com/rust-lang/rust/pull/118310#issuecomment-2016940014 below for where we got to recently that made it ready for review.
---
There are dozens of reasonable ways to implement `Ord::cmp` for integers using comparison, bit-ops, and branches. Those differences are irrelevant at the rust level, however, so we can make things better by adding `BinOp::Cmp` at the MIR level:
1. Exactly how to implement it is left up to the backends, so LLVM can use whatever pattern its optimizer best recognizes and cranelift can use whichever pattern codegens the fastest.
2. By not inlining those details for every use of `cmp`, we drastically reduce the amount of MIR generated for `derive`d `PartialOrd`, while also making it more amenable to MIR-level optimizations.
Having extremely careful `if` ordering to μoptimize resource usage on broadwell (#63767) is great, but it really feels to me like libcore is the wrong place to put that logic. Similarly, using subtraction [tricks](https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign) (#105840) is arguably even nicer, but depends on the optimizer understanding it (https://github.com/llvm/llvm-project/issues/73417) to be practical. Or maybe [bitor is better than add](https://discourse.llvm.org/t/representing-in-ir/67369/2?u=scottmcm)? But maybe only on a future version that [has `or disjoint` support](https://discourse.llvm.org/t/rfc-add-or-disjoint-flag/75036?u=scottmcm)? And just because one of those forms happens to be good for LLVM, there's no guarantee that it'd be the same form that GCC or Cranelift would rather see -- especially given their very different optimizers. Not to mention that if LLVM gets a spaceship intrinsic -- [which it should](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Suboptimal.20inlining.20in.20std.20function.20.60binary_search.60/near/404250586) -- we'll need at least a rustc intrinsic to be able to call it.
As for simplifying it in Rust, we now regularly inline `{integer}::partial_cmp`, but it's quite a large amount of IR. The best way to see that is with 8811efa88b (diff-d134c32d028fbe2bf835fef2df9aca9d13332dd82284ff21ee7ebf717bfa4765R113) -- I added a new pre-codegen MIR test for a simple 3-tuple struct, and this PR change it from 36 locals and 26 basic blocks down to 24 locals and 8 basic blocks. Even better, as soon as the construct-`Some`-then-match-it-in-same-BB noise is cleaned up, this'll expose the `Cmp == 0` branches clearly in MIR, so that an InstCombine (#105808) can simplify that to just a `BinOp::Eq` and thus fix some of our generated code perf issues. (Tracking that through today's `if a < b { Less } else if a == b { Equal } else { Greater }` would be *much* harder.)
---
r? `@ghost`
But first I should check that perf is ok with this
~~...and my true nemesis, tidy.~~
The original proposal allows reference patterns
with "compatible" mutability, however it's not clear
what that means so for now we require an exact match.
I don't know the type system code well, so if something
seems to not make sense it's probably because I made a
mistake
Add detection of [Partial]Ord methods in the `ambiguous_wide_pointer_comparisons` lint
Partially addresses https://github.com/rust-lang/rust/issues/121264 by adding diagnostics items for PartialOrd and Ord methods, detecting such diagnostics items as "binary operation" and suggesting the correct replacement.
I also took the opportunity to change the suggestion to use new methods `.cast()` on `*mut T` an d `*const T`.
Simplify trim-paths feature by merging all debuginfo options together
This PR simplifies the trim-paths feature by merging all debuginfo options together, as described in https://github.com/rust-lang/rust/issues/111540#issuecomment-1994010274.
And also do some correctness fixes found during the review.
cc `@weihanglo`
r? `@michaelwoerister`
Match ergonomics 2024: implement mutable by-reference bindings
Implements the mutable by-reference bindings portion of match ergonomics 2024 (#123076), with the `mut ref`/`mut ref mut` syntax, under feature gate `mut_ref`.
r? `@Nadrieril`
`@rustbot` label A-patterns A-edition-2024
Eliminate `UbChecks` for non-standard libraries
The purpose of this PR is to allow other passes to treat `UbChecks` as constants in MIR for optimization after #122629.
r? RalfJung
Codegen const panic messages as function calls
This skips emitting extra arguments at every callsite (of which there
can be many). For a librustc_driver build with overflow checks enabled,
this cuts 0.7MB from the resulting shared library (see [perf]).
A sample improvement from nightly:
```
leaq str.0(%rip), %rdi
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdx
movl $25, %esi
callq *_ZN4core9panicking5panic17h17cabb89c5bcc999E@GOTPCREL(%rip)
```
to this PR:
```
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdi
callq *_RNvNtNtCsduqIKoij8JB_4core9panicking11panic_const23panic_const_div_by_zero@GOTPCREL(%rip)
```
[perf]: https://perf.rust-lang.org/compare.html?start=a7e4de13c1785819f4d61da41f6704ed69d5f203&end=64fbb4f0b2d621ff46d559d1e9f5ad89a8d7789b&stat=instructions:u
Let codegen decide when to `mem::swap` with immediates
Making `libcore` decide this is silly; the backend has so much better information about when it's a good idea.
Thus this PR introduces a new `typed_swap` intrinsic with a fallback body, and replaces that fallback implementation when swapping immediates or scalar pairs.
r? oli-obk
Replaces #111744, and means we'll never need more libs PRs like #111803 or #107140
This skips emitting extra arguments at every callsite (of which there
can be many). For a librustc_driver build with overflow checks enabled,
this cuts 0.7MB from the resulting binary.
Experimental feature postfix match
This has a basic experimental implementation for the RFC postfix match (rust-lang/rfcs#3295, #121618). [Liaison is](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Postfix.20Match.20Liaison/near/423301844) ```@scottmcm``` with the lang team's [experimental feature gate process](https://github.com/rust-lang/lang-team/blob/master/src/how_to/experiment.md).
This feature has had an RFC for a while, and there has been discussion on it for a while. It would probably be valuable to see it out in the field rather than continue discussing it. This feature also allows to see how popular postfix expressions like this are for the postfix macros RFC, as those will take more time to implement.
It is entirely implemented in the parser, so it should be relatively easy to remove if needed.
This PR is split in to 5 commits to ease review.
1. The implementation of the feature & gating.
2. Add a MatchKind field, fix uses, fix pretty.
3. Basic rustfmt impl, as rustfmt crashes upon seeing this syntax without a fix.
4. Add new MatchSource to HIR for Clippy & other HIR consumers
Several (doc) comments were super outdated or didn't provide enough context.
Some doc comments shoved everything in a single paragraph without respecting
the fact that the first paragraph should be a single sentence because rustdoc
treats these as item descriptions / synopses on module pages.
Add a never type option to make diverging blocks `()`
More experiments for ~~the blood god~~ T-lang!
Usage example:
```rust
#![allow(internal_features)]
#![feature(never_type, rustc_attrs)]
#![rustc_never_type_options(diverging_block_default = "unit")]
fn main() {
let _: u8 = { //~ error: expected `u8`, found `()`
return;
};
}
```
r? compiler-errors
I'm not sure how I feel about parsing the attribute every time we create `FnCtxt`. There must be a better way to do this, right?
Making `libcore` decide this is silly; the backend has so much better information about when it's a good idea.
So introduce a new `typed_swap` intrinsic with a fallback body, but replace that implementation for immediates and scalar pairs.
Expose the Freeze trait again (unstably) and forbid implementing it manually
non-emoji version of https://github.com/rust-lang/rust/pull/121501
cc #60715
This trait is useful for generic constants (associated consts of generic traits). See the test (`tests/ui/associated-consts/freeze.rs`) added in this PR for a usage example. The builtin `Freeze` trait is the only way to do it, users cannot work around this issue.
It's also a useful trait for building some very specific abstrations, as shown by the usage by the `zerocopy` crate: https://github.com/google/zerocopy/issues/941
cc ```@RalfJung```
T-lang signed off on reexposing this unstably: https://github.com/rust-lang/rust/pull/121501#issuecomment-1969827742
Distinguish between library and lang UB in assert_unsafe_precondition
As described in https://github.com/rust-lang/rust/pull/121583#issuecomment-1963168186, `assert_unsafe_precondition` now explicitly distinguishes between language UB (conditions we explicitly optimize on) and library UB (things we document you shouldn't do, and maybe some library internals assume you don't do).
`debug_assert_nounwind` was originally added to avoid the "only at runtime" aspect of `assert_unsafe_precondition`. Since then the difference between the macros has gotten muddied. This totally revamps the situation.
Now _all_ preconditions shall be checked with `assert_unsafe_precondition`. If you have a precondition that's only checkable at runtime, do a `const_eval_select` hack, as done in this PR.
r? RalfJung
Optimize `Symbol::integer` by utilizing in-place formatting
This PR optimize `Symbol::integer` by utilizing `itoa` in-place formatting instead of going through a dynamically allocated `String` and the format machinery.
<details>
For some context: I was profiling `rustc --check-cfg` with callgrind and due to the way we currently setup all the targets and we end-up calling `Symbol::integer` multiple times for all the targets. Using `itoa` reduced the number of instructions.
</details>
Add asm goto support to `asm!`
Tracking issue: #119364
This PR implements asm-goto support, using the syntax described in "future possibilities" section of [RFC2873](https://rust-lang.github.io/rfcs/2873-inline-asm.html#asm-goto).
Currently I have only implemented the `label` part, not the `fallthrough` part (i.e. fallthrough is implicit). This doesn't reduce the expressive though, since you can use label-break to get arbitrary control flow or simply set a value and rely on jump threading optimisation to get the desired control flow. I can add that later if deemed necessary.
r? ``@Amanieu``
cc ``@ojeda``
Add new `pattern_complexity` attribute to add possibility to limit and check recursion in pattern matching
Needed for https://github.com/rust-lang/rust-analyzer/issues/9528.
This PR adds a new attribute only available when running rust testsuite called `pattern_complexity` which allows to set the maximum recursion for the pattern matching. It is quite useful to ensure the complexity doesn't grow, like in `tests/ui/pattern/usefulness/issue-118437-exponential-time-on-diagonal-match.rs`.
r? `@Nadrieril`
Add stubs in IR and ABI for `f16` and `f128`
This is the very first step toward the changes in https://github.com/rust-lang/rust/pull/114607 and the [`f16` and `f128` RFC](https://rust-lang.github.io/rfcs/3453-f16-and-f128.html). It adds the types to `rustc_type_ir::FloatTy` and `rustc_abi::Primitive`, and just propagates those out as `unimplemented!` stubs where necessary.
These types do not parse yet so there is no feature gate, and it should be okay to use `unimplemented!`.
The next steps will probably be AST support with parsing and the feature gate.
r? `@compiler-errors`
cc `@Nilstrieb` suggested breaking the PR up in https://github.com/rust-lang/rust/pull/120645#issuecomment-1925900572
Adjust printing for RPITITs
1. Call RPITITs `{synthetic#N}` instead of `{opaque#N}`.
2. Fall back to printing the RPITIT like an opaque even when printed as an `AliasTy`, just like we do for `ty::Alias`.
You could argue that (2.) is misleading, but I believe it's more consistent than naming `{synthetic#N}`, which I assume approximately nobody knows where that def path name comes from.
r? lcnr
Add "algebraic" fast-math intrinsics, based on fast-math ops that cannot return poison
Setting all of LLVM's fast-math flags makes our fast-math intrinsics very dangerous, because some inputs are UB. This set of flags permits common algebraic transformations, but according to the [LangRef](https://llvm.org/docs/LangRef.html#fastmath), only the flags `nnan` (no nans) and `ninf` (no infs) can produce poison.
And this uses the algebraic float ops to fix https://github.com/rust-lang/rust/issues/120720
cc `@orlp`
macro_rules: Preserve all metavariable spans in a global side table
This PR preserves spans of `tt` metavariables used to pass tokens to declarative macros.
Such metavariable spans can then be used in span combination operations like `Span::to` to improve all kinds of diagnostics.
Spans of non-`tt` metavariables are currently kept in nonterminal tokens, but the long term plan is remove all nonterminal tokens from rustc parser and rely on the proc macro model with invisible delimiters (#114647, #67062).
In particular, `NtIdent` nonterminal (corresponding to `ident` metavariables) becomes easy to remove when this PR lands (#119412 does it).
The metavariable spans are kept in a global side table keyed by `Span`s of original tokens.
The alternative to the side table is keeping them in `SpanData` instead, but the performance regressions would be large because any spans from tokens passed to declarative macros would stop being inline and would work through span interner instead, and the penalty would be paid even if we never use the metavar span for the given original span.
(But also see the comment on `fn maybe_use_metavar_location` describing the map collision issues with the side table approach.)
There are also other alternatives - keeping the metavar span in `Token` or `TokenTree`, but associating it with `Span` itsel is the most natural choice because metavar spans are used in span combining operations, and those operations are not necessarily tied to tokens.
fixes#117448
For example unnecessary imports in std::prelude that can be eliminated:
```rust
use std::option::Option::Some;//~ WARNING the item `Some` is imported redundantly
use std::option::Option::None; //~ WARNING the item `None` is imported redundantly
```
Implement intrinsics with fallback bodies
fixes#93145 (though we can port many more intrinsics)
cc #63585
The way this works is that the backend logic for generating custom code for intrinsics has been made fallible. The only failure path is "this intrinsic is unknown". The `Instance` (that was `InstanceDef::Intrinsic`) then gets converted to `InstanceDef::Item`, which represents the fallback body. A regular function call to that body is then codegenned. This is currently implemented for
* codegen_ssa (so llvm and gcc)
* codegen_cranelift
other backends will need to adjust, but they can just keep doing what they were doing if they prefer (though adding new intrinsics to the compiler will then require them to implement them, instead of getting the fallback body).
cc `@scottmcm` `@WaffleLapkin`
### todo
* [ ] miri support
* [x] default intrinsic name to name of function instead of requiring it to be specified in attribute
* [x] make sure that the bodies are always available (must be collected for metadata)
Rollup of 11 pull requests
Successful merges:
- #120765 (Reorder diagnostics API)
- #120833 (More internal emit diagnostics cleanups)
- #120899 (Gracefully handle non-WF alias in `assemble_alias_bound_candidates_recur`)
- #120917 (Remove a bunch of dead parameters in functions)
- #120928 (Add test for recently fixed issue)
- #120933 (check_consts: fix duplicate errors, make importance consistent)
- #120936 (improve `btree_cursors` functions documentation)
- #120944 (Check that the ABI of the instance we are inlining is correct)
- #120956 (Clean inlined type alias with correct param-env)
- #120962 (Add myself to library/std review)
- #120972 (fix ICE for deref coercions with type errors)
r? `@ghost`
`@rustbot` modify labels: rollup
Suppress suggestions in derive macro
close#118809
I suppress warnings inside derive macros.
For example, the compiler emits following error by a program described in https://github.com/rust-lang/rust/issues/118809#issuecomment-1852256687 with a suggestion that indicates invalid syntax.
```
error[E0308]: `?` operator has incompatible types
--> src/main.rs:3:17
|
3 | #[derive(Debug, Deserialize)]
| ^^^^^^^^^^^ expected `u32`, found `u64`
|
= note: `?` operator cannot convert from `u64` to `u32`
= note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
|
3 | #[derive(Debug, Deserialize.try_into().unwrap())]
| ++++++++++++++++++++
For more information about this error, try `rustc --explain E0308`.
error: could not compile `serde_test` (bin "serde_test") due to 2 previous errors
```
In this PR, suggestions to cast are suppressed.
```
error[E0308]: `?` operator has incompatible types
--> src/main.rs:3:17
|
3 | #[derive(Debug, Deserialize)]
| ^^^^^^^^^^^ expected `u32`, found `u64`
|
= note: `?` operator cannot convert from `u64` to `u32`
= note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
For more information about this error, try `rustc --explain E0308`.
error: could not compile `serde_test` (bin "serde_test") due to 2 previous errors
```
Invert diagnostic lints.
That is, change `diagnostic_outside_of_impl` and `untranslatable_diagnostic` from `allow` to `deny`, because more than half of the compiler has been converted to use translated diagnostics.
This commit removes more `deny` attributes than it adds `allow` attributes, which proves that this change is warranted.
r? ````@davidtwco````
Remove some `unchecked_claim_error_was_emitted` calls
We want to drive the number of these calls down as much as possible. This PR gets rid of a bunch of them.
r? ``@oli-obk``
- In `emit_producing_error_guaranteed`, only allow `Level::Error`.
- In `emit_diagnostic`, only produce `ErrorGuaranteed` for `Level` and
`DelayedBug`. (Not `Bug` or `Fatal`. They don't need it, because the
relevant `emit` methods abort.)
- Add/update various comments.
Rework support for async closures; allow them to return futures that borrow from the closure's captures
This PR implements a new lowering for async closures via `TyKind::CoroutineClosure` which handles the curious relationship between the closure and the coroutine that it returns.
I wrote up a bunch in [this hackmd](https://hackmd.io/`@compiler-errors/S1HvqQxca)` which will be copied to the dev guide after this PR lands, and hopefully left sufficient comments in the source code explaining why this change is as large as it is.
This also necessitates that they begin implementing the `AsyncFn`-family of traits, rather than the `Fn`-family of traits -- if you need `Fn` implementations, you should probably use the non-sugar `|| async {}` syntax instead.
Notably this PR does not yet implement `async Fn()` syntax sugar for bounds, but I expect to add those soon (**edit:** #120392). For now, users must use `AsyncFn()` traits directly, which necessitates adding the `async_fn_traits` feature gate as well. I will add this as a follow-up very soon.
r? oli-obk
This is based on top of #120322, but that PR is minimal.
That is, change `diagnostic_outside_of_impl` and
`untranslatable_diagnostic` from `allow` to `deny`, because more than
half of the compiler has be converted to use translated diagnostics.
This commit removes more `deny` attributes than it adds `allow`
attributes, which proves that this change is warranted.
Revert outdated version of "Add the wasm32-wasi-preview2 target"
An outdated version of #119616 was merged in rollup #120309.
This reverts those changes to enable #119616 to “retain the intended diff” after a rebase.
```@rylev``` has agreed that this would be the cleanest approach with respect to the history.
Unblocks #119616.
r? ```@petrochenkov``` or compiler or libs
Add the `min_exhaustive_patterns` feature gate
## Motivation
Pattern-matching on empty types is tricky around unsafe code. For that reason, current stable rust conservatively requires arms for empty types in all but the simplest case. It has long been the intention to allow omitting empty arms when it's safe to do so. The [`exhaustive_patterns`](https://github.com/rust-lang/rust/issues/51085) feature allows the omission of all empty arms, but hasn't been stabilized because that was deemed dangerous around unsafe code.
## Proposal
This feature aims to stabilize an uncontroversial subset of exhaustive_patterns. Namely: when `min_exhaustive_patterns` is enabled and the data we're matching on is guaranteed to be valid by rust's operational semantics, then we allow empty arms to be omitted. E.g.:
```rust
let x: Result<T, !> = foo();
match x { // ok
Ok(y) => ...,
}
let Ok(y) = x; // ok
```
If the place is not guaranteed to hold valid data (namely ptr dereferences, ref dereferences (conservatively) and union field accesses), then we keep stable behavior i.e. we (usually) require arms for the empty cases.
```rust
unsafe {
let ptr: *const Result<u32, !> = ...;
match *ptr {
Ok(x) => { ... }
Err(_) => { ... } // still required
}
}
let foo: Result<u32, &!> = ...;
match foo {
Ok(x) => { ... }
Err(&_) => { ... } // still required because of the dereference
}
unsafe {
let ptr: *const ! = ...;
match *ptr {} // already allowed on stable
}
```
Note that we conservatively consider that a valid reference can point to invalid data, hence we don't allow arms of type `&!` and similar cases to be omitted. This could eventually change depending on [opsem decisions](https://github.com/rust-lang/unsafe-code-guidelines/issues/413). Whenever opsem is undecided on a case, we conservatively keep today's stable behavior.
I proposed this behavior in the [`never_patterns`](https://github.com/rust-lang/rust/issues/118155) feature gate but it makes sense on its own and could be stabilized more quickly. The two proposals nicely complement each other.
## Unresolved Questions
Part of the question is whether this requires an RFC. I'd argue this doesn't need one since there is no design question beyond the intent to omit unreachable patterns, but I'm aware the problem can be framed in ways that require design (I'm thinking of the [original never patterns proposal](https://smallcultfollowing.com/babysteps/blog/2018/08/13/never-patterns-exhaustive-matching-and-uninhabited-types-oh-my/), which would frame this behavior as "auto-nevering" happening).
EDIT: I initially proposed a future-compatibility lint as part of this feature, I don't anymore.
remove StructuralEq trait
The documentation given for the trait is outdated: *all* function pointers implement `PartialEq` and `Eq` these days. So the `StructuralEq` trait doesn't really seem to have any reason to exist any more.
One side-effect of this PR is that we allow matching on some consts that do not implement `Eq`. However, we already allowed matching on floats and consts containing floats, so this is not new, it is just allowed in more cases now. IMO it makes no sense at all to allow float matching but also sometimes require an `Eq` instance. If we want to require `Eq` we should adjust https://github.com/rust-lang/rust/pull/115893 to check for `Eq`, and rule out float matching for good.
Fixes https://github.com/rust-lang/rust/issues/115881
Add `AsyncFn` family of traits
I'm proposing to add a new family of `async`hronous `Fn`-like traits to the standard library for experimentation purposes.
## Why do we need new traits?
On the user side, it is useful to be able to express `AsyncFn` trait bounds natively via the parenthesized sugar syntax, i.e. `x: impl AsyncFn(&str) -> String` when experimenting with async-closure code.
This also does not preclude `AsyncFn` becoming something else like a trait alias if a more fundamental desugaring (which can take many[^1] different[^2] forms) comes around. I think we should be able to play around with `AsyncFn` well before that, though.
I'm also not proposing stabilization of these trait names any time soon (we may even want to instead express them via new syntax, like `async Fn() -> ..`), but I also don't think we need to introduce an obtuse bikeshedding name, since `AsyncFn` just makes sense.
## The lending problem: why not add a more fundamental primitive of `LendingFn`/`LendingFnMut`?
Firstly, for `async` closures to be as flexible as possible, they must be allowed to return futures which borrow from the async closure's captures. This can be done by introducing `LendingFn`/`LendingFnMut` traits, or (equivalently) by adding a new generic associated type to `FnMut` which allows the return type to capture lifetimes from the `&mut self` argument of the trait. This was proposed in one of [Niko's blog posts](https://smallcultfollowing.com/babysteps/blog/2023/05/09/giving-lending-and-async-closures/).
Upon further experimentation, for the purposes of closure type- and borrow-checking, I've come to the conclusion that it's significantly harder to teach the compiler how to handle *general* lending closures which may borrow from their captures. This is, because unlike `Fn`/`FnMut`, the `LendingFn`/`LendingFnMut` traits don't form a simple "inheritance" hierarchy whose top trait is `FnOnce`.
```mermaid
flowchart LR
Fn
FnMut
FnOnce
LendingFn
LendingFnMut
Fn -- isa --> FnMut
FnMut -- isa --> FnOnce
LendingFn -- isa --> LendingFnMut
Fn -- isa --> LendingFn
FnMut -- isa --> LendingFnMut
```
For example:
```
fn main() {
let s = String::from("hello, world");
let f = move || &s;
let x = f(); // This borrows `f` for some lifetime `'1` and returns `&'1 String`.
```
That trait hierarchy means that in general for "lending" closures, like `f` above, there's not really a meaningful return type for `<typeof(f) as FnOnce>::Output` -- it can't return `&'static str`, for example.
### Special-casing this problem:
By splitting out these traits manually, and making sure that each trait has its own associated future type, we side-step the issue of having to answer the questions of a general `LendingFn`/`LendingFnMut` implementation, since the compiler knows how to generate built-in implementations for first-class constructs like async closures, including the required future types for the (by-move) `AsyncFnOnce` and (by-ref) `AsyncFnMut`/`AsyncFn` trait implementations.
[^1]: For example, with trait transformers, we may eventually be able to write: `trait AsyncFn = async Fn;`
[^2]: For example, via the introduction of a more fundamental "`LendingFn`" trait, plus a [special desugaring with augmented trait aliases](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Lending.20closures.20and.20Fn*.28.29.20-.3E.20impl.20Trait/near/408471480).
Replacement of #114390: Add new intrinsic `is_var_statically_known` and optimize pow for powers of two
This adds a new intrinsic `is_val_statically_known` that lowers to [``@llvm.is.constant.*`](https://llvm.org/docs/LangRef.html#llvm-is-constant-intrinsic).` It also applies the intrinsic in the int_pow methods to recognize and optimize the idiom `2isize.pow(x)`. See #114390 for more discussion.
While I have extended the scope of the power of two optimization from #114390, I haven't added any new uses for the intrinsic. That can be done in later pull requests.
Note: When testing or using the library, be sure to use `--stage 1` or higher. Otherwise, the intrinsic will be a noop and the doctests will be skipped. If you are trying out edits, you may be interested in [`--keep-stage 0`](https://rustc-dev-guide.rust-lang.org/building/suggested.html#faster-builds-with---keep-stage).
Fixes#47234Resolves#114390
`@Centri3`
Add a new `wasm32-wasi-preview2` target
This is the initial implementation of the MCP https://github.com/rust-lang/compiler-team/issues/694 creating a new tier 3 target `wasm32-wasi-preview2`. That MCP has been seconded and will most likely be approved in a little over a week from now. For more information on the need for this target, please read the [MCP](https://github.com/rust-lang/compiler-team/issues/694).
There is one aspect of this PR that will become insta-stable once these changes reach a stable compiler:
* A new `target_family` named `wasi` is introduced. This target family incorporates all wasi targets including `wasm32-wasi` and its derivative `wasm32-wasi-preview1-threads`. The difference between `target_family = wasi` and `target_os = wasi` will become much clearer when `wasm32-wasi` is renamed to `wasm32-wasi-preview1` and the `target_os` becomes `wasm32-wasi-preview1`. You can read about this target rename in [this MCP](https://github.com/rust-lang/compiler-team/issues/695) which has also been seconded and will hopefully be officially approved soon.
Additional technical details include:
* Both `std::sys::wasi_preview2` and `std::os::wasi_preview2` have been created and mostly use `#[path]` annotations on their submodules to reach into the existing `wasi` (soon to be `wasi_preview1`) modules. Over time the differences between `wasi_preview1` and `wasi_preview2` will grow and most like all `#[path]` based module aliases will fall away.
* Building `wasi-preview2` relies on a [`wasi-sdk`](https://github.com/WebAssembly/wasi-sdk) in the same way that `wasi-preview1` does (one must include a `wasi-root` path in the `Config.toml` pointing to sysroot included in the wasi-sdk). The target should build against [wasi-sdk v21](https://github.com/WebAssembly/wasi-sdk/releases/tag/wasi-sdk-21) without modifications. However, the wasi-sdk itself is growing [preview2 support](https://github.com/WebAssembly/wasi-sdk/pull/370) so this might shift rapidly. We will be following along quickly to make sure that building the target remains possible as the wasi-sdk changes.
* This requires a [patch to libc](https://github.com/rylev/rust-libc/tree/wasm32-wasi-preview2) that we'll need to land in conjunction with this change. Until that patch lands the target won't actually build.
Consolidate logic around resolving built-in coroutine trait impls
Deduplicates a lot of code. Requires defining a new lang item for `Coroutine::resume` for consistency, but it seems not harmful at worst, and potentially later useful at best.
r? oli-obk
Fix overflow check
Make MIRI choose the path randomly and rename the intrinsic
Add back test
Add miri test and make it operate on `ptr`
Define `llvm.is.constant` for primitives
Update MIRI comment and fix test in stage2
Add const eval test
Clarify that both branches must have the same side effects
guaranteed non guarantee
use immediate type instead
Co-Authored-By: Ralf Jung <post@ralfj.de>
Improved collapse_debuginfo attribute, added command-line flag
Improved attribute collapse_debuginfo with variants: `#[collapse_debuginfo=(no|external|yes)]`.
Added command-line flag for default behaviour.
Work-in-progress: will add more tests.
cc https://github.com/rust-lang/rust/issues/100758
This removes emit_enum_variant and the emit_usize calls that resulted
in. In libcore this eliminates 17% of leb128, taking us from 8964488 to
7383842 leb128's serialized.
Improved support of collapse_debuginfo attribute for macros.
Added walk_chain_collapsed function to consider collapse_debuginfo attribute in parent macros in call chain.
Fixed collapse_debuginfo attribute processing for cranelift (there was if/else branches error swap).
cc https://github.com/rust-lang/rust/issues/100758
rustc_span: More consistent span combination operations
Also add more tests for using `tt` in addition to `ident`, and some other minor tweaks, see individual commits.
This is a part of https://github.com/rust-lang/rust/pull/119412 that doesn't yet add side tables for metavariable spans.
rustc_span: Optimize syntax context comparisons
Including comparisons with root context.
- `eq_ctxt` doesn't require retrieving full `SpanData`, or taking the span interner lock twice.
- Checking `SyntaxContext` for "rootness" is cheaper than extracting a full outer `ExpnData` for it and checking *it* for rootness.
The internal lint for `eq_ctxt` is also tweaked to detect `a.ctxt() != b.ctxt()` in addition to `a.ctxt() == b.ctxt()`.
Avoid specialization in the metadata serialization code
With the exception of a perf-only specialization for byte slices and byte vectors.
This uses the same trick of introducing a new trait and having the Encodable and Decodable derives add a bound to it as used for TyEncoder/TyDecoder. The new code is clearer about which encoder/decoder uses which impl and it reduces the dependency of rustc on specialization, making it easier to remove support for specialization entirely or turn it into a construct that is only allowed for perf optimizations if we decide to do this.
Replace a number of FxHashMaps/Sets with stable-iteration-order alternatives
This PR replaces almost all of the remaining `FxHashMap`s in query results with either `FxIndexMap` or `UnordMap`. The only case that is missing is the `EffectiveVisibilities` struct which turned out to not be straightforward to transform. Once that is done too, we can remove the `HashStable` implementation from `HashMap`.
The first commit adds the `StableCompare` trait which is a companion trait to `StableOrd`. Some types like `Symbol` can be compared in a cross-session stable way, but their `Ord` implementation is not stable. In such cases, a `StableCompare` implementation can be provided to offer a lightweight way for stable sorting. The more heavyweight option is to sort via `ToStableHashKey`, but then sorting needs to have access to a stable hashing context and `ToStableHashKey` can also be expensive as in the case of `Symbol` where it has to allocate a `String`.
The rest of the commits are rather mechanical and don't overlap, so they are best reviewed individually.
Part of [MCP 533](https://github.com/rust-lang/compiler-team/issues/533).
In the past it did create a fresh expansion, but now, after surviving a number of refactorings, it does not.
Now it's just a thin wrapper around `apply_mark`.
custom mir: make it clear what the return block is
Custom MIR recently got support for specifying the "unwind action", so now there's two things coming after the actual call part of `Call` terminators. That's not very self-explaining so I propose we change the syntax to imitate keyword arguments:
```
Call(popped = Vec::pop(v), ReturnTo(drop), UnwindContinue())
```
Also fix some outdated docs and add some docs to `Call` and `Drop`.
StableCompare is a companion trait to `StableOrd`. Some types like `Symbol` can be compared in a cross-session stable way, but their `Ord` implementation is not stable. In such cases, a `StableOrd` implementation can be provided to offer a lightweight way for stable sorting. (The more heavyweight option is to sort via `ToStableHashKey`, but then sorting needs to have access to a stable hashing context and `ToStableHashKey` can also be expensive as in the case of `Symbol` where it has to allocate a `String`.)
Unify SourceFile::name_hash and StableSourceFileId
This PR adapts the existing `StableSourceFileId` type so that it can be used instead of the `name_hash` field of `SourceFile`. This simplifies a few things that were kind of duplicated before.
The PR should also fix issues https://github.com/rust-lang/rust/issues/112700 and https://github.com/rust-lang/rust/issues/115835, but I was not able to reproduce these issues in a regression test. As far as I can tell, the root cause of these issues is that the id of the originating crate is not hashed in the `HashStable` impl of `Span` and thus cache entries that should have been considered invalidated were loaded. After this PR, the `stable_id` field of `SourceFile` includes information about the originating crate, so that ICE should not occur anymore.
Instead, we store just the local crate hash as a bare u64. On decoding,
we recombine it with the crate's stable crate ID stored separately in
metadata. The end result is that we save ~8 bytes/DefIndex in metadata
size.
One key detail here is that we no longer distinguish in encoded metadata
between present and non-present DefPathHashes. It used to be highly
likely we could distinguish as we used DefPathHash::default(), an
all-zero representation. However in theory even that is fallible as
nothing strictly prevents the StableCrateId from being zero.
Add lint against ambiguous wide pointer comparisons
This PR is the resolution of https://github.com/rust-lang/rust/issues/106447 decided in https://github.com/rust-lang/rust/issues/117717 by T-lang.
## `ambiguous_wide_pointer_comparisons`
*warn-by-default*
The `ambiguous_wide_pointer_comparisons` lint checks comparison of `*const/*mut ?Sized` as the operands.
### Example
```rust
let ab = (A, B);
let a = &ab.0 as *const dyn T;
let b = &ab.1 as *const dyn T;
let _ = a == b;
```
### Explanation
The comparison includes metadata which may not be expected.
-------
This PR also drops `clippy::vtable_address_comparisons` which is superseded by this one.
~~One thing: is the current naming right? `invalid` seems a bit too much.~~
Fixes https://github.com/rust-lang/rust/issues/117717
detects redundant imports that can be eliminated.
for #117772 :
In order to facilitate review and modification, split the checking code and
removing redundant imports code into two PR.
rustc_arena: add `alloc_str`
Two places called `from_utf8_unchecked` for strings from `alloc_slice`,
and one's SAFETY comment said this was for lack of `alloc_str` -- so
let's just add that instead!
Two places called `from_utf8_unchecked` for strings from `alloc_slice`,
and one's SAFETY comment said this was for lack of `alloc_str` -- so
let's just add that instead!
Add `never_patterns` feature gate
This PR adds the feature gate and most basic parsing for the experimental `never_patterns` feature. See the tracking issue (https://github.com/rust-lang/rust/issues/118155) for details on the experiment.
`@scottmcm` has agreed to be my lang-team liaison for this experiment.
By default, `newtype_index!` types get a default `Encodable`/`Decodable`
impl. You can opt out of this with `custom_encodable`. Opting out is the
opposite to how Rust normally works with autogenerated (derived) impls.
This commit inverts the behaviour, replacing `custom_encodable` with
`encodable` which opts into the default `Encodable`/`Decodable` impl.
Only 23 of the 59 `newtype_index!` occurrences need `encodable`.
Even better, there were eight crates with a dependency on
`rustc_serialize` just from unused default `Encodable`/`Decodable`
impls. This commit removes that dependency from those eight crates.
Custom MIR: Support cleanup blocks
Cleanup blocks are declared with `bb (cleanup) = { ... }`.
`Call` and `Drop` terminators take an additional argument describing the unwind action, which is one of the following:
* `UnwindContinue()`
* `UnwindUnreachable()`
* `UnwindTerminate(reason)`, where reason is `ReasonAbi` or `ReasonInCleanup`
* `UnwindCleanup(block)`
Also support unwind resume and unwind terminate terminators:
* `UnwindResume()`
* `UnwindTerminate(reason)`
Cleanup blocks are declared with `bb (cleanup) = { ... }`.
`Call` and `Drop` terminators take an additional argument describing the
unwind action, which is one of the following:
* `UnwindContinue()`
* `UnwindUnreachable()`
* `UnwindTerminate(reason)`, where reason is `ReasonAbi` or `ReasonInCleanup`
* `UnwindCleanup(block)`
Also support unwind resume and unwind terminate terminators:
* `UnwindResume()`
* `UnwindTerminate(reason)`
Remove `-Zkeep-hygiene-data`.
It was added way back in #28585 under the name `-Zkeep-mtwt-tables`. The justification was:
> This is so that the resolution results can be used after analysis,
> potentially for tool support.
There are no uses of significance in the code base, and various Google searches for both option names (and variants) found nothing of interest. I think this can safely be removed.
r? `@davidtwco`
It was added way back in #28585 under the name `-Zkeep-mtwt-tables`. The
justification was:
> This is so that the resolution results can be used after analysis,
> potentially for tool support.
There are no uses of significance in the code base, and various Google
searches for both option names (and variants) found nothing of interest.
@petrochenkov says removing this part (and it's only part) of the
hygiene data is dubious. It doesn't seem that big, so let's just keep it
around.
Make `FatalErrorMarker` lower priority than other panics
This makes `FatalErrorMarker` lower priority than other panics in a parallel sections. If any other panics occur, they will be unwound instead of `FatalErrorMarker`. This ensures `rustc` will exit with the correct error code on ICEs.
This fixes https://github.com/rust-lang/rust/issues/116659.
Give a better diagnostic for missing parens in Fn* bounds
Fixes#108109
It would be nice to try and recover here, but I'm not sure it's worth the effort, especially as the bounds on the recovered function would be incorrect.
Pretty print `Fn` traits in `rustc_on_unimplemented`
I don't think that users really ever should need to think about `Fn*` traits' tupled args for a simple trait error.
r? diagnostics
Most notably, this commit changes the `pub use crate::*;` in that file
to `use crate::*;`. This requires a lot of `use` items in other crates
to be adjusted, because everything defined within `rustc_span::*` was
also available via `rustc_span::source_map::*`, which is bizarre.
The commit also removes `SourceMap::span_to_relative_line_string`, which
is unused.
The comment just below the first one describes how the `impl !Send for
FatalError` makes it impossible to `panic!(FatalError)`.
And the second one should be `panic_any` instead of `panic!`.
- Sort dependencies and features sections.
- Add `tidy` markers to the sorted sections so they stay sorted.
- Remove empty `[lib`] sections.
- Remove "See more keys..." comments.
Excluded files:
- rustc_codegen_{cranelift,gcc}, because they're external.
- rustc_lexer, because it has external use.
- stable_mir, because it has external use.
Implement `gen` blocks in the 2024 edition
Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078
This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.
An example usage of `gen` blocks is
```rust
fn foo() -> impl Iterator<Item = i32> {
gen {
yield 42;
for i in 5..18 {
if i.is_even() { continue }
yield i * 2;
}
}
}
```
The limitations (to be resolved) of the implementation are listed in the tracking issue
Avoid a `track_errors` by bubbling up most errors from `check_well_formed`
I believe `track_errors` is mostly papering over issues that a sufficiently convoluted query graph can hit. I made this change, while the actual change I want to do is to stop bailing out early on errors, and instead use this new `ErrorGuaranteed` to invoke `check_well_formed` for individual items before doing all the `typeck` logic on them.
This works towards resolving https://github.com/rust-lang/rust/issues/97477 and various other ICEs, as well as allowing us to use parallel rustc more (which is currently rather limited/bottlenecked due to the very sequential nature in which we do `rustc_hir_analysis::check_crate`)
cc `@SparrowLii` `@Zoxc` for the new `try_par_for_each_in` function
Implement rustc part of RFC 3127 trim-paths
This PR implements (or at least tries to) [RFC 3127 trim-paths](https://github.com/rust-lang/rust/issues/111540), the rustc part. That is `-Zremap-path-scope` with all of it's components/scopes.
`@rustbot` label: +F-trim-paths
The `rustc_span::FileName` enum already differentiates between real
files and "fake" files such as `<anon>`. We do not need to artificially
forbid real file names from ending in `>`.
Partially outline code inside the panic! macro
This outlines code inside the panic! macro in some cases. This is split out from https://github.com/rust-lang/rust/pull/115562 to exclude changes to rustc.
Prototype using const generic for simd_shuffle IDX array
cc https://github.com/rust-lang/rust/issues/85229
r? `@workingjubilee` on the design
TLDR: there is now a `fn simd_shuffle_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;` intrinsic that allows replacing
```rust
simd_shuffle(a, b, const { stuff })
```
with
```rust
simd_shuffle_generic::<_, _, {&stuff}>(a, b)
```
which makes the compiler implementations much simpler, if we manage to at some point eliminate `simd_shuffle`.
There are some issues with this today though (can't do math without bubbling it up in the generic arguments). With this change, we can start porting the simple cases and get better data on the others.
Fall back to the unoptimized implementation in read_binary_file if File::metadata lies
Fixes https://github.com/rust-lang/rust/issues/115458
r? `@jackh726` because you approved the previous PR
Accept additional user-defined syntax classes in fenced code blocks
Part of #79483.
This is a re-opening of https://github.com/rust-lang/rust/pull/79454 after a big update/cleanup. I also converted the syntax to pandoc as suggested by `@notriddle:` the idea is to be as compatible as possible with the existing instead of having our own syntax.
## Motivation
From the original issue: https://github.com/rust-lang/rust/issues/78917
> The technique used by `inline-c-rs` can be ported to other languages. It's just super fun to see C code inside Rust documentation that is also tested by `cargo doc`. I'm sure this technique can be used by other languages in the future.
Having custom CSS classes for syntax highlighting will allow tools like `highlight.js` to be used in order to provide highlighting for languages other than Rust while not increasing technical burden on rustdoc.
## What is the feature about?
In short, this PR changes two things, both related to codeblocks in doc comments in Rust documentation:
* Allow to disable generation of `language-*` CSS classes with the `custom` attribute.
* Add your own CSS classes to a code block so that you can use other tools to highlight them.
#### The `custom` attribute
Let's start with the new `custom` attribute: it will disable the generation of the `language-*` CSS class on the generated HTML code block. For example:
```rust
/// ```custom,c
/// int main(void) {
/// return 0;
/// }
/// ```
```
The generated HTML code block will not have `class="language-c"` because the `custom` attribute has been set. The `custom` attribute becomes especially useful with the other thing added by this feature: adding your own CSS classes.
#### Adding your own CSS classes
The second part of this feature is to allow users to add CSS classes themselves so that they can then add a JS library which will do it (like `highlight.js` or `prism.js`), allowing to support highlighting for other languages than Rust without increasing burden on rustdoc. To disable the automatic `language-*` CSS class generation, you need to use the `custom` attribute as well.
This allow users to write the following:
```rust
/// Some code block with `{class=language-c}` as the language string.
///
/// ```custom,{class=language-c}
/// int main(void) {
/// return 0;
/// }
/// ```
fn main() {}
```
This will notably produce the following HTML:
```html
<pre class="language-c">
int main(void) {
return 0;
}</pre>
```
Instead of:
```html
<pre class="rust rust-example-rendered">
<span class="ident">int</span> <span class="ident">main</span>(<span class="ident">void</span>) {
<span class="kw">return</span> <span class="number">0</span>;
}
</pre>
```
To be noted, we could have written `{.language-c}` to achieve the same result. `.` and `class=` have the same effect.
One last syntax point: content between parens (`(like this)`) is now considered as comment and is not taken into account at all.
In addition to this, I added an `unknown` field into `LangString` (the parsed code block "attribute") because of cases like this:
```rust
/// ```custom,class:language-c
/// main;
/// ```
pub fn foo() {}
```
Without this `unknown` field, it would generate in the DOM: `<pre class="language-class:language-c language-c">`, which is quite bad. So instead, it now stores all unknown tags into the `unknown` field and use the first one as "language". So in this case, since there is no unknown tag, it'll simply generate `<pre class="language-c">`. I added tests to cover this.
Finally, I added a parser for the codeblock attributes to make it much easier to maintain. It'll be pretty easy to extend.
As to why this syntax for adding attributes was picked: it's [Pandoc's syntax](https://pandoc.org/MANUAL.html#extension-fenced_code_attributes). Even if it seems clunkier in some cases, it's extensible, and most third-party Markdown renderers are smart enough to ignore Pandoc's brace-delimited attributes (from [this comment](https://github.com/rust-lang/rust/pull/110800#issuecomment-1522044456)).
## Raised concerns
#### It's not obvious when the `language-*` attribute generation will be added or not.
It is added by default. If you want to disable it, you will need to use the `custom` attribute.
#### Why not using HTML in markdown directly then?
Code examples in most languages are likely to contain `<`, `>`, `&` and `"` characters. These characters [require escaping](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/pre) when written inside the `<pre>` element. Using the \`\`\` code blocks allows rustdoc to take care of escaping, which means doc authors can paste code samples directly without manually converting them to HTML.
cc `@poliorcetics`
r? `@notriddle`
Make useless_ptr_null_checks smarter about some std functions
This teaches the `useless_ptr_null_checks` lint that some std functions can't ever return null pointers, because they need to point to valid data, get references as input, etc.
This is achieved by introducing an `#[rustc_never_returns_null_ptr]` attribute and adding it to these std functions (gated behind bootstrap `cfg_attr`).
Later on, the attribute could maybe be used to tell LLVM that the returned pointer is never null. I don't expect much impact of that though, as the functions are pretty shallow and usually the input data is already never null.
Follow-up of PR #113657Fixes#114442
Rework `no_coverage` to `coverage(off)`
As discussed at the tail of https://github.com/rust-lang/rust/issues/84605 this replaces the `no_coverage` attribute with a `coverage` attribute that takes sub-parameters (currently `off` and `on`) to control the coverage instrumentation.
Allows future-proofing for things like `coverage(off, reason="Tested live", issue="#12345")` or similar.
